docs: def get_color(self):
          """ Return the array of rgba colors (same order as lStruct) """
          col = np.full((self._dStruct['nObj'],4), np.nan)
          ii = 0
          for k in self._dStruct['lorder']:
              k0, k1 = k.split('_')
              col[ii,:] = self._dStruct['dObj'][k0][k1].get_color()
              ii += 1
          return col